JPH0343935B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a vapor reflow soldering device, and relates to a printed wiring board, particularly a so-called flat pack element and resistor in which electrode terminals are taken out in a flat manner in four directions. The present invention relates to a vapor reflow soldering apparatus suitable for soldering high-density mounted printed wiring boards using semiconductor chip components such as capacitors.

[Conventional technology] In recent years, high-density mounting of electronic components on printed wiring boards has progressed more and more, but since the soldering work for mounting electronic components such as semiconductor chips on printed wiring boards is the final process of the line, it is difficult to solder. Since the quality of soldering affects the performance of electronic components, soldering technology has come to be seen as an important technology even on the production line.

Recently, due to the need to improve the uniformity of temperature distribution in the furnace where soldering work is carried out and to avoid harmful overheating of electronic components, steam with a high density relative to air has been used as a heat medium and its latent heat of condensation has been utilized. Vapor reflow (steam remelting) type soldering equipment, which heats the workpiece by steam, is attracting attention.

For example, as described in Japanese Patent Application Laid-Open No. 60-106502, this device mounts electronic components on the solder pattern of a printed wiring board, and heats the printed wiring board with a high specific gravity relative to air as described above. This is a soldering device equipped with a vapor tank called a vapor reflow tank, which heats and melts solder by passing it through a saturated vapor medium to solder electronic components onto a printed wiring board.

The heat carrier used in such a steam tank is a fluorine-based inert organic agent, and the saturated steam has a molecular weight of, for example, about 820 g/mole under the applied temperature and pressure. Some have about 20 times the specific gravity to air. Such a heat medium is very expensive, and various recovery devices have been devised to recover used steam for reuse.

First, a horizontal vapor reflow soldering apparatus using a typical conventional belt conveyor will be described with reference to FIG.

FIG. 9 is a configuration diagram of a conventional vapor reflow soldering apparatus.

In FIG. 9, 1' is a steam tank in which a steam generating tank for boiling and heating the heat medium 11 and a furnace tank for heating and melting the solder of the object to be processed are integrated.
Reference numeral 2' denotes a carry-in side conveyance path for carrying soldering members 13 related to objects to be processed into the steam tank 1', 3' denotes a carry-out side conveyance path for carrying out the processed soldering members 13, and 4 denotes the conveyance path. It is a conveyor for

Reference numeral 5 denotes a heater provided at the lower part of the steam tank 1', that is, the steam generation tank section; 6, an upper cooling coil provided at the upper part of the steam tank 1'; and 7', a heater provided at the outer periphery of the conveyance path 2' on the carry-in side. The provided carry-in side cooling coil 8' is a carry-out side cooling coil provided on the outer periphery of the carry-out side conveying path 3'.
9 is a carry-in side exhaust port, and 10 is a carry-out side exhaust port.

The operation of the vapor reflow soldering apparatus configured as described above will be explained.

The saturated steam 12 of the heat medium that is boiled and evaporated by the heater 5 immersed in the heat medium 11 stored in the bottom of the steam tank 1', that is, the steam generating tank, rises to the top of the steam tank 1', and its height is equal to that of the upper part. It is controlled by the condensing action of the cooling coil 6.

The saturated steam 12 that has flowed into the carry-in side conveyance path 2' and the carry-out side conveyance path 3' is cooled by the carry-in side cooling coil 7' and the carry-out side cooling coil 8', and the amount of steam is gradually reduced. A small amount of remaining steam is exhausted to the atmosphere from the carry-in side exhaust port 9 and the carry-out side exhaust port 10.

On the other hand, the workpiece for soldering electronic components to a printed wiring board, that is, the soldering member 13,
It is carried into the carry-in side conveyance path 2' by the conveyor 4,
The solder comes into contact with the saturated steam 12 and is gradually heated, enters the steam tank 1', and is heated and melted by the latent heat of condensation of the saturated steam 12, thereby soldering the components together.

At this time, a part of the saturated steam 12 is condensed and liquefied, falls, and accumulates in the lower part of the steam tank 1', that is, in the lower part of the steam generation tank.

The soldered member 13 that has been processed enters the discharge-side conveyance path 3', is gradually cooled, and is discharged from the apparatus.

[Problems to be Solved by the Invention] In such a vapor reflow soldering apparatus, the following problems occur.

1 When the solder of the soldering member 13 is melted in the steam tank 1', a part of the solder and a part of the flux, which is a solvent for soldering, applied to the soldering member are condensed and liquefied together with the heat medium. It falls to the lower part of the steam tank 1' and mixes with the accumulated heat medium 11.

The flux mixed with the heat medium 11 adheres to the surface of the heater 5 that is immersed in the heat medium 11, reducing the electric heating performance and causing the
There is a problem in that maintenance is expensive because it corrodes the metal.

2. The flux mixed with the heat medium 11 prevents the heat medium 11 from boiling, causing a delay in response to changes in heat load, and causing temporary difficulty in maintaining the height of the steam level of the saturated steam 12. In order to prevent this, it is necessary to increase the amount of evaporation, which increases the demand for electric power for the heater 5 and the amount of cooling water, resulting in an increase in the running cost of the device.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and it is possible to reliably separate the flux from the mixed liquid of the heat medium and the flux using a small and simple device, thereby separating the heat medium and the flux. The object is to provide a vapor reflow soldering device that reduces mixing, facilitates maintenance, and reduces lining costs.

[Means for Solving the Problems] In order to achieve the above object, the configuration of the vapor reflow soldering apparatus according to the present invention is such that the solder of the workpiece is heated by bringing saturated vapor of a heating medium into contact with the workpiece. It has a steam tank for melting and soldering, and at least a steam generating tank for boiling and evaporating the heating medium, and a return for recovering a mixed liquid of the heating medium and flux that has been condensed and liquefied by heating the object to be processed. In a vapor reflow soldering apparatus equipped with a tank and a flux separator for removing flux from the recovered mixed liquid, the flux separator is located at a midpoint between the height difference between the return tank and the steam generation tank. This flux separation device consists of a liquid pool part separated by a weir and a flux removal part equipped with a filter on the overflow side of the weir, and the mixed liquid is transferred from the return tank to the liquid pool part by a height difference. The return tank and the liquid pool are connected by piping so that the liquid mixture flows into the liquid pool, and as the temperature of the mixed liquid that flows into the liquid pool decreases, the upper flux and the lower heat are separated into upper and lower parts due to a difference in specific gravity. overflowing the weir with a medium;
A downstream part of the filter of the flux removal section and the steam generation tank are connected by piping so that the flux is collected by the filter and the heat medium that has passed through the filter is sent to the steam generation tank. It is.

[Examples] Examples of the present invention will be described below with reference to FIGS. 1 to 8.

First, FIG. 1 is a sectional view showing the configuration of a vapor reflow soldering apparatus according to an embodiment of the present invention, FIG. 2 is a sectional view taken along the line A-A in FIG. 1, and FIG. The sectional view taken along the line B-B in FIG. 1, and FIG. 3b,
FIG. 1 is a sectional view taken along the line CC in FIG. 1. In the figure, the same reference numerals as in FIG. 9 indicate parts equivalent to those in the prior art, and therefore the description thereof will be omitted.

In FIGS. 1 and 2, reference numeral 1 denotes a steam tank in which a steam generating tank 1a for boiling and heating a heat medium 11 and a tank part 1b for heating and melting solder of a soldering member 13 related to an object to be processed are formed as an integrated tank. , 2 is a carry-in side carry-out path for carrying the soldering members 13 into the steam tank 1, 3 is a carry-out side transport path for carrying out the processed soldering members 13, and 4 is a conveyor for carrying the soldering members 13.

7 is a carry-in side cooling coil provided in the carry-in side conveyance path 2; 8 is a carry-out side cooling coil provided in the carry-out side conveyance path 3; and 14 is an opening of the carry-in side conveyance path 2.

Reference numeral 15 denotes a return tank disposed directly below the furnace tank section 1b in the steam tank 1, and this return tank 15 carries the saturated steam 12.
serves as a tank for receiving the liquefied heat medium that heats the soldering member 13 and then condenses and liquefies and falls.

17-1 is a return pipe for recovering the liquefied heat medium from the liquid receiving part 2a of the carry-in side conveyance path 2 to the steam generating tank 1a, and 17-2 is a return pipe for recovering the liquefied heat medium from the liquid receiving part 3a of the carrying-out side conveying path 3 A return pipe 19 for recovering the liquefied heat medium to the tank 1a is a partition wall that constitutes the furnace tank section 1b in the steam tank 1.

Reference numeral 25 denotes a flux separator for removing flux mixed into the heat medium condensed and liquefied in the furnace tank section 1b in the steam tank 1. A liquid reservoir 25b located in the middle of the difference and partitioned by a weir 25a and a filter 2 are installed at the overflow part of the weir 25a.
The flux removing section 25c has a flux removing section 25c having a diameter of 6.

24 is a return tank 15 and a flux separation device 25
This pipe 24 is a pipe that sends the mixed liquid in the return tank 15 to the liquid pool 25b.

27 is a pipe connecting the downstream part of the filter of the flux removing section 25c in the flux separator 25 and the steam generation tank 1a, and this pipe 27 is
Filter 26 provided in flux removal section 25c
This is a return pipe that returns the heat medium from which the flux has been removed to the steam generation tank 1a.

The operation of the vapor reflow soldering apparatus of this embodiment configured as described above will be explained.

The heat medium 11 accumulated in the bottom of the steam tank 1, that is, the steam generation tank 1a, is heated by the heater 5 and boils and evaporates, and the saturated steam 12 of the heat medium rises, and the flow line shown by the arrow in FIG. 2 rises. As shown, a portion heats the lower surface of the soldering member 13, and the remaining portion heats the upper surface of the soldering member 13 through the gap 18 between the partition wall 19 and the peripheral wall of the steam tank 1.

At this time, a part of the saturated steam 12 is condensed and liquefied and falls together with flux, etc., and accumulates in the return tank 15, and the rest is left in the carry-in side conveyance path 2 and the carry-out side conveyance path 2.
leaks to.

If there is no soldering member 13 on the conveyor 4, the density of the saturated steam 12 is significantly higher than that of air. As shown, the leaked saturated steam 12 is transferred to the conveyor 4 and the discharge side wall gap 2.
2 and enters the discharge side lower space 23, is condensed and liquefied by the discharge side cooling coil 8, and falls into the liquid receiving part 3a.

The liquefied heat medium that has fallen into the liquid receiving portion 3a is recovered to the heat medium storage portion of the steam generation tank 1a through the return pipe 17-2.

When there is a soldering member 13 on the conveyor 4, the saturated steam 12 fills the inlet side wall gap 20 as shown by the inlet conveyance path 2 in FIG. 1 and the streamlined arrow in FIG. 3a. It enters the lower space 21 on the carry-in side, is condensed and liquefied by the cooling coil 7 on the carry-in side, and falls into the liquid receiving part 2a.

The liquefied heat medium that has fallen into the liquid receiving portion 2a is recovered to the heat medium storage portion of the steam generation tank 1a through the return pipe 17-1.

Note that the functions of condensing and liquefying the heat medium and recovering the heat medium are the same on both the carry-in side and the carry-out side.

The liquefied heat transfer medium containing flux that has fallen into the return tank 15 is transferred to the return tank 15 and the flux separator 2.
The flux flows down the pipe 24 according to the height difference with respect to the flux separator 25 and flows into the liquid reservoir 25b of the flux separator 25.
As the temperature of the liquefied heat medium (mixture of heat medium and flux) that has flowed into the liquid reservoir 25b gradually decreases, the flux solidifies from within the liquefied heat medium and moves to the upper part of the liquid due to the difference in specific gravity. flux,
The heating medium separates below it. The flux and heat medium accumulated in the liquid reservoir section 25b sequentially overflow from the weir 25a to the flux removing section 25c, and as shown in the figure, the flux removing section 25c is filtered by a filter 26 provided on the overflow side of the weir 25a.
The flux solidified by passing through is collected.

The heat medium from which the flux has been removed and which has passed through the filter 26 is transferred to the flux removing section 2 according to the height difference between the flux separator 25 and the steam generation tank 1a.
It flows down the return pipe 27 from the downstream part of the filter 5c and is collected in the steam generation tank 1a.

According to this embodiment, the following effects are achieved.

1. The heating medium 11 of the steam generation tank 1a is still contaminated with flux, etc., so that no deposits are deposited on the surface of the heater 5 immersed in the heating medium 11, so there is no deterioration in heat transfer performance, and heating is possible. Maintenance intervals such as inspection and cleaning of the heater 5 can be extended, making maintenance easier.

Moreover, since there is nothing that prevents boiling and evaporation of the heat medium 11, there is no delay in response to changes in heat load, and power consumption of the heater 5 can be saved.

2 The amount of heat medium containing flux is
Since only a small amount of flux is condensed from the soldering member 13 in the furnace tank portion 1b and dropped into the return tank 15, the flux separator 25 can be made smaller and simpler.

Also, the mixed liquid is passed through the pipe 24 that connects the return tank 15 and the liquid reservoir 25b, and the heat medium from which the flux has been separated is passed through the return pipe 27 that connects the flux removal unit 25c and the steam generation tank 1a, using the height difference. Because it flows as a fluid, there is no need for a circulation pump, reducing costs and power.

Next, other embodiments of the present invention are shown in FIGS. 4 and 5.
This will be explained with reference to the figures.

Here, FIG. 4 is a sectional view showing the configuration of a vapor reflow soldering apparatus according to another embodiment of the present invention, and FIG. 5 is a sectional view taken along the line D-D in FIG. , Components having the same reference numerals as those in FIGS. 1 and 2 are the same parts as in the previous embodiment, so their explanation will be omitted.

In the embodiment shown in FIGS. 4 and 5, two return tanks 15A and 16 are provided in the steam tank 1.

The first return tank 15A and the second return tank 16 are
As shown in FIG.
The first return tank 15A is provided with saucers on both sides,
The second return tank 16 is provided with a saucer in the center, and is configured to receive the liquefied heat medium that passes through the first return tank 15A and falls.

The pipe 24 leading from the return tank to the flux separator 25 is connected to the branch pipe 24 from the first return tank 15A.
a. A branch pipe 24b is provided from the second return tank 16 to join the pipe 24.

According to this embodiment, the same effects as the embodiments shown in FIGS. 2 and 3 are expected, and as shown by the streamlines of arrows in FIG. It is easier to fit under the 13.

It should be noted that since it is easy to provide more stages of return tanks for the heat medium, illustrations and explanations of the embodiments will be omitted here.

Next, still another embodiment of the present invention will be described with reference to FIGS. 6 and 7.

Here, FIG. 6 is a sectional view showing the configuration of a vapor reflow soldering apparatus according to still another embodiment of the present invention, and FIG. 7 is a sectional view taken along the line E-E in FIG. , those with the same symbols as in Figures 1 and 2 are:
Since this is the same part as the previous embodiment, the explanation thereof will be omitted.

The embodiments shown in FIGS. 6 and 7 show examples in which the bottom of the return tank for the condensed and liquefied heat medium does not come into contact with the boiled and evaporated heat medium.

Further, in this embodiment, the steam generation tank and the steam tank 1 have an integral structure that can be separated from the steam generation tank.

The return tank 15B is equipped with a shielding plate 30 on its back side, and the boiling and evaporated heat medium is returned to the return tank 15B.
It is configured so that it does not come into direct contact with the saucer part of the container.

29 is a steam generation tank that is separable from the steam tank 1 via a flange 29a. The shielding plate 30 provided in the return tank 15B is connected to the steam generation tank 29.
It is formed so as to be connected to the flange 29a of.

The saturated steam 12 of the heat medium boiled and evaporated by the heater 5 in the steam generation tank 29 rises through the gap 28 between the return tank 15B and the steam tank 1, and a part of it heats the lower surface of the soldering member 13. , the rest is bulkhead 1
The upper surface of the soldering member 13 is heated through the gap 18 between the soldering member 9 and the peripheral wall of the steam tank 1. Since the subsequent operations are exactly the same as those described in the embodiments of FIGS. 1 and 4, their explanation will be omitted.

According to the embodiments shown in FIGS. 6 and 7, the same effects as those of the previous embodiments can be expected, and the saturated steam 12 as the heat medium can effectively heat the soldering member 13.

In addition, since the steam generation tank 29 is separated from the steam tank 1, the lower part of the steam tank 1 can be made smaller, and the belt of the conveyor 4 can be passed between the return tank 15B and the steam generation section, making it possible to reduce the length of the belt. becomes the shortest, and the recovery efficiency of the heat medium also improves.

Next, still another embodiment of the present invention will be described with reference to FIG.

FIG. 8 is a cross-sectional view showing the configuration of a vapor reflow soldering apparatus according to still another embodiment of the present invention, and in the figure, the same reference numerals as in FIG. Since this is the same part as the example, its explanation will be omitted.

The embodiment shown in FIG. 8 is an example in which the steam generation tank is arranged independently.

In FIG. 8, 15C represents soldering member 1
This return tank 15C forms the bottom of the steam tank 1A. 31 is a steam generation tank provided separately from the steam tank 1A, and this steam generation tank 31
is arranged at a lower level than the return tank 15C and the flux separator 25. 32 is a duct that connects the side surface of the return tank 15C (above the storage surface of the liquefied heat medium) and the top surface of the steam generation tank 31.

The saturated steam 12 as a heat medium generated from the steam generation tank 31 enters the steam tank 1 from the side of the return tank 15C via the duct 32, and heats the soldering member 13. Since the subsequent operation is the same as that described in the embodiments of FIGS. 1 and 4, the description thereof will be omitted.

According to the embodiment shown in FIG. 8, the same effects as those of the above-mentioned embodiment can be expected, and the following effects are also obtained.

Since the steam generation tank 31 is separated from the steam tank 1,
The heaviest steam generation tank 31 can be supported individually, so that the steam tank 1, the carry-in side conveyance path 2, the carry-out side conveyance path 3, etc. can be made thinner and lighter.

Moreover, maintenance of the steam generation tank 31 and the return tank 15C becomes easy.

[Effects of the Invention] As described above, according to the present invention, flux separation from a mixed liquid of a heat medium and a flux can be performed by
It is possible to provide a vapor reflow soldering device that can reliably perform soldering with a small and simplified device, reduces mixing of heat medium and flux, facilitates maintenance, and lowers running costs.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the configuration of a vapor reflow soldering apparatus according to an embodiment of the present invention, FIG. 2 is a sectional view taken along the line A-A in FIG. 1, and FIG.
is a sectional view taken along the line B-B in FIG. 1, FIG. 3b is a sectional view taken along the line C-C in FIG. 1, and FIG. 4 is a vapor reflow solder according to another embodiment of the present invention. A cross-sectional view showing the configuration of the attaching device, FIG.
6 is a cross-sectional view showing the configuration of a vapor reflow soldering apparatus according to still another embodiment of the present invention; FIG. 7 is a cross-sectional view taken along the line E-E in FIG. 6. , FIG. 8 is a sectional view showing the configuration of a vapor reflow soldering apparatus according to still another embodiment of the present invention, and FIG. 9 is a configuration diagram of a conventional vapor reflow soldering apparatus. 1, 1A...Steam tank, 1a...Steam generation tank, 5
... Heater, 11 ... Heat medium, 12 ... Saturated steam, 13 ... Soldering member, 15, 15B,
15C... Return tank, 15A... First return tank, 1
6... Second return tank, 17-1, 17-2... Return piping, 24... Piping, 24a, 24b... Branch pipe, 25... Flux separation device, 25a...
Weir, 25b...liquid pool, 25c...flux removal section, 26...filter, 27...return piping, 29, 31...steam generation tank, 30...shielding plate, 32...duct.

Claims (1)

[Scope of Claims] 1. A steam tank in which soldering is performed by bringing saturated steam of a heat medium into contact with a workpiece and heating and melting the solder of the workpiece, and at least steam that boils and evaporates the heat medium. Vapor reflow soldering equipped with a generation tank, a return tank that collects a mixed liquid of flux and a heating medium that is condensed and liquefied by heating the object to be processed, and a flux separation device that removes flux from the collected mixed liquid. In the attachment device, the flux separator is located at a midpoint between the height difference between the return tank and the steam generation tank, and the flux separator is located between a liquid pool partitioned by a weir and an overflow side of the weir. a flux removal section equipped with a filter; the return tank and the liquid reservoir are connected by piping so that the mixed liquid flows from the return tank into the liquid reservoir according to a difference in height; The upper flux and the lower heat medium separated into upper and lower parts due to the difference in specific gravity as the temperature of the mixed liquid flowing into the liquid mixture decreases, are caused to overflow the weir, and the flux is collected by the filter,
A vapor reflow soldering apparatus characterized in that a downstream part of the filter of the flux removal section and the steam generation tank are connected by piping so that the heat medium that has passed through the filter is sent to the steam generation tank. . 2. In what is stated in claim 1,
A vapor reflow soldering apparatus characterized in that a shielding plate is provided on the back side of the return tank so that saturated steam generated in the steam generation tank does not come into direct contact with the lower part of the return tank. 3 In what is stated in claim 1,
A vapor reflow soldering device characterized in that a steam generation tank and a return tank are connected through a duct, and the saturated steam generated in the steam generation tank does not come into direct contact with the lower part of the return tank. 4 In what is stated in claim 1,
A vapor reflow soldering device characterized in that the return tank is configured in either one stage or multiple stages.